Wireless telegraphy



H. RICHMOND WIRELESS TELEGRAPHY Filed July 23. 1921 awvantoz H. RlCHMOND Patented Jan. 3, 1 928.

rates HAROLD RICHMOND, OF LONDON, ENGLAND, ASSIGNOR TO RADIO CORPORATION OF i AMERICA, A CORPORATION OF DELAVIABE.

WIRELESS TELDGRAPHY.

Application filed July 23, 1921, Serial No. 487,124, and in Great Britain April 25, 1918.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. L, 1313.)

This invention relates to improvements in apparatus for eliminating interference in wireless telegraphy whereby signals coming from a different direction from that of the signals it is desired to receive may, even though of the same wave length, be eliminated without materially reducing the strength of the desired signals.

It is well known that if a receiver be connected to a coil which can be rotated in two independent fields produced by two directional aerials at right angles to each other, as in the radiogoniometer, there is a posi* tion of the coil in which no sound is caused by signals from a particular direction.

According to the present invention, and with the object of avoiding reduction in the strength of the desired signals, I produce an unsymmetrical field for the coil by adjusting the coupling between the coil and the two aerials so as to strengthen one of the two component fields resulting from the jamming station relatively to the other. This has the efiect of twisting the resultant field that is set up by the jamming station from its normal position to a position approximately at right angles to the field that is set up by the station it is desired to receive. The coil is then rotated to a position of maximum coupling with the desired field and minimum coupling with the objectionable field.

According to a modification of the invention 'I produce the same effect in cases where the inductance coils of the two aerials are not all arranged in a single plane by dividing the rotatable coil into two parts, one of which is coupled to the inductance of one aerial and the other to the other, and adj usting the couplings so that the two aerials produce an unsymmetrical action on the receiving circuit.

My invention is illustrated by the accompanying diagrams, in which Fig. 1 is a diagrammatic representation of an aerial circuit and a receiving circuit embodying the invention, and Fig. 2 is a similar view of a modification.

In Figure 1, A B C D and E F G H are two frame aerials situated at right angles to each other. These aerials may be rectangular or may consist of directive systems of any known type.-

In these aerials are connected inductances I J K L and condensers M N. An inductance O is coupled to the coils I and J and to the coils K and L and is connected to the receiving circuit. The distance of I J K and L from O can be adjusted so that the' coupling between each aerial and the receiving circuit may be varied independently so as to produce an unsymmetrical field.

In practice it is preferable to set out the aerials so that the plane of one frame lies in the direction of the station it is desired to receive, the other being at right angles to this direction. It is also essential that the coils I and J should be so situated with respect to K and L that no mutual action can occur between them. a

Figure 2 shows another arrangement which is substantially the same as that shown in Figure 1 except that the coils I and J are not in the same plane as the coils K and L and the inductance O is divided into two parts P, P With this arrangement the coils may be so mounted that when the coupling between I, J and P is a maximum, the coupling between K, L and P is a minimum. In use it is found best to have the aerial whose plane is in the direction of the station it is desired to receive as loosely coupled as possible without unduly weakening the signals, and the other or balancing aerial as tightly coupled as possible. This arrangement also reduces to a minimum the efiect of any mutual action between the two circuits. I

The'two aerials should be tuned to exactly the same frequency. l/Vhen this condition is obtained the currents produced in the aerials by a jamming station will be identical in phase and by adjusting the positions of the coils I J K L the field resulting from the amming station can, in effect, be twisted to a direction approximately at right angles to the field set up by the station it is desired to receive. The rotatable coil is then positioned so that it has a maximum coupling with the desired field and a minimum coupling with' the objectionable field; consequently no indication results from the objectionable signals in the receiver, while the signals to be received are not unduly weakened.

Having described my invention; what I claim is:

1. The methodv of eliminating.interfering signals Witha iradiogoniometer having a rotating coil coupled to two aerials which conv sists in producing an unsymmetrical relation between the fields of the coupling means and the rotating coil, and adjusting the angular ing the rotating coil to produce unsyniinetri cal 'lcoupling; with the ,aerials, and. then a d- 'justing the. angular; relation ofthe, coil to eliminate interference. 1

3.;T-hen1ethod of eliniiiiatin i eerie-rin I -s signals 'vVl-LD a rotating co l twoiaeiial rad1o- :-gon on 1eter sys n WlllCll CODSlStS in tuning theaenals to thesarne ire ,uenc dis osing the -rotating coil to'produce unsymmetri cal coupling with the aerials, and then ad- 'nstins thean nlarrelation of the c0il to' no a i V eliminate interference, and-receiving desired signals Withfthe coil in this position.

4. The method of. eliminating.interferings igna-ls witha rotatinglcoil two aerial radio.- gon on eter systemwhich consists in tuning the aer als to the same frequency, disposing the rotating coil to produce unsymmetrical v couplingwith the aerials and then adjusting the. angular relation of the coil to eliminate interference. f v

v; 54A directional .radio receiving system comprising a. pair of directional aerials, a

receivingcircuit having a rotatable coil, and

separate cfoupling coilsffor coupling each of he aerials to the. rotatable coil, arranged. so

' thatthe fields produced by each of said coupling coils. are unequal in strength at the effectiveycenter ofwsaid rotatable coil when equal strengthcurrent's flow in said aerials. V 6 A directional rad o 1'6061V111g system coinpr si-nga pair ofaerials having different ilectivity, a receivingjcircuit,having a rotatable coil,, and means. ,for coupling the aerialsto, the. rotatable coil said means and said coils being so disposed that at the effective center of said rotatable coilthe fields produced by said coupling means arennsame ifrequcmcy,' having different directiVit-y,

r. A;- directional radio receiving system" compr sing a pair otaerials tuned-gto rt he a receiving circuit having a rotatablecoil; and'inea ns for coupling the aerials'to the r0-1 .tatable cOilQ said inea'ns being disposed-at different distances "fromsaicFrotatablecoil so that theefields produced .by said coupling means are i'insyninietrical at the eiiectire cen te'r 'ot'said rotatable'coil. "85th directional radio:receivingi system c0n prising, ,a'pair ofcrossedloopiae TalS receiving circuit having a rotatable c neanstor. coupling .the aerials to thejr a ablecoih said means being disposed a 1 r ent distances from said rotatable "co that the fieldsgproduced by said; coup means areuneqlialcatthe e flfective Ge re, said rotatable coil. a 9; A; Qdirectional radio receiving f in comprising a pair-of crossedjloopherial receiving circuit havingamtatableicoil coupling coilsconnectedfin. said riaisjdm. posed at different, distancesfrom thefrotatr g o l. 1 l' f f .10. A directionalradio receiving syste'ni Y i con iprisinga pair of crossedloop aerialsiand a receiving circuitlia ving a rotatablelcoilg each 01 said aerials havinga pair of coupling 41 I coils,. the. coils of each, pair being disposed on opposite sides oft-he rotating econ; e a el; V i ei -e' d sp sed, a f en d stem l therefrom. x V a j V 11. A ,cdirectional indie.- receiving [systemcomprising apair .of-aerials havingfdilier n11 directii ityyone of said aerials being disposed} 5 for maximum reception of signalsfareceiyingcircuit having a'irotatablecoil; and means for coupling aeralst-o the rotatable coil, 1 ,1 said meansqand said. coils. beingfrelatedcso that the fields produced by saidco, plin'g ,nieans areunsy-niinetrical at the .e

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